HFU HF Underground
Technical Topics => Equipment => Topic started by: ChrisSmolinski on December 03, 2013, 1649 UTC
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I came across this paper, and thought it would be interesting to others here:
Receiving Phased Array with Small Electric or Magnetic Active Wideband Elements. Experimental Performance Evaluation
http://www.lz1aq.signacor.com/docs/phased-array/2-ele_phased_array11.pdf
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On a related note, anyone done a basic phased setup with a couple of monopole verticals and a MFJ-1025 or similar entry-level phasing device? I have tossed around the idea, but I already have multiple verticals littering the backyard landscape.
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Nice find, Chris!
Back in the day, I cobbled together a two element phased array using a pair of lower Q (~50) resonant loops with a homebrew phasing unit. I had some pretty good (read encouraging) results, and I have always wanted to follow up this initial venture into phased arrays when time permitted.
I will post more when I find the notebook with details.
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Thanks for the link! I will probably be putting up a short 2 vertical phased array for receiving within the next year.
He also has some good info on Small Wideband Magnetic Loops that I have been looking at lately.
http://www.lz1aq.signacor.com/docs/wsml/wideband-active-sm-loop-antenna.htm (http://www.lz1aq.signacor.com/docs/wsml/wideband-active-sm-loop-antenna.htm)
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OIC!
Hey refmo, thanks for posting that link! I have a copy of that page in my files, and have been impressed with what looks like a pretty good design.
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I will probably be putting up a short 2 vertical phased array for receiving within the next year.
That is on my project list as well, but it gets tossed down to low priority for whatever reasons, such as looking at more antennas in the backyard. ;) If/when I get around to the project, my first attempt will likely use a MFJ-1025 or similar basic "noise canceller" for phasing control, thus my earlier inquiry.
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Hello Rob,
I just joined the group and your post about phased antennas was one of the first I read. I now use two 20' verticals fed into a MFJ 1026 phase box for NDB and MW listening. It works well most of the time after dark but nulling signals during the day is a problem. I initially tried two amplified loops, same plane and then at 90 degrees to each other but the nulls were never very deep.
The verticals are only about 25' apart at present and when it warms up a little I'll separate them more. I have to two very strong local stations to use as a daytime standard and when I get the antennas moved apart I'll report back. Dave
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Rob: Have you tried phasing any of your existing verticals??
dbs: From what I have read on the subject, 20 feet spacing would be difficult to work with. 60 feet would be much better, especially on those low frequencies.
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I didn't plan the location of the antennas it's just that the antenna bases are mounted to chain link fence posts that are about 25' apart. I was planing on moving one antenna along the fence line another post or two to see if the nulls improve on my day time test stations. Too cold here to fool around with it now. Maybe next week.
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No phasing work with the existing stuff here. Too many variances in antenna lengths, tunings, etc.
About separation, some say 1/8 WL at the lowest desired freq is the minimum recommendation. However, 1/4 WL is probably a (much) better approach. I have not done any modelling on such a system, though, so YMMV.
If/when done, I am also debating on the verticals to be used. The S9v43 is of particular interest, but I am close enough to the coast to be concerned about wind loading.
Decisions.... ;)
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Also, dbs, welcome to the community. :)
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Thank you.
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I'm busy building the physical antenna elements and hope to have the kit running next month ;)
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I finally moved one vertical antenna along the fence line, they are now 52' apart(ran out of coax). The null on the local news station stayed about the same, from +10 over S9 to about S2. The other local station was about +20 over S9 and nulled to about S3 before the move and now after the move with careful nulling it's only S5. I don't see any other differences after the move so I'm putting the vertical back to its original location. Dave